/Engine/Source/Editor/BlueprintGraph/Classes/EdGraphSchema_K2.h
Sets the string to the specified pin; even if it is invalid it is still set.
virtual void TrySetDefaultValue ( [UEdGraphPin](API\Runtime\Engine\EdGraph\UEdGraphPin) & Pin, const [FString](API\Runtime\Core\Containers\FString) & NewDefaultValue, bool bMarkAsModified ) const